1. Field of the Invention
The invention relates to a throttle valve.
2. Description of Related Art
Conventionally, in a gas tank provided in a fuel cell vehicle or the like, a valve device is provided to control the supply of high-pressure hydrogen gas into the tank, and the discharge of the high-pressure hydrogen gas stored inside the tank. The valve device includes a body in which a gas flow passage is provided, the gas flow passage providing communication between the inside and the outside of the gas tank; and a valve mechanism that controls the flow of the hydrogen gas through the gas flow passage. The gas flow passage is connected to a pipe extending from an external device (for example a supply source that supplies the hydrogen gas) via a joint fitted to the body (for example, refer to Japanese Patent Application Publication No. 2013-29161 (JP 2013-29161A).
More specifically, as shown in FIG. 6, in a valve device described in JP 2013-29161A, a body 121 has an fitting hole 123 into which a joint 122 is fitted. The body 121 also has a supply passage 124 that is opened to the bottom surface of the fitting hole 123, and that serves as a gas flow passage through which hydrogen gas is supplied into a gas tank.
A check valve 132 is provided in the supply passage 124. The check valve 132 suppresses the discharge (release) of hydrogen gas to the outside through the fitting hole 123. When hydrogen gas is not supplied, the check valve 132 suppresses the discharge of hydrogen gas from the supply passage 124 in the following manner. A valve element 137 is urged toward a valve seat 136 by the pressure of hydrogen gas and the urging force of an urging member 138 and is seated at the valve seat 136 to close a valve orifice 135 of the valve seat 136.
As shown in FIG. 6, the joint 122 is formed such that a throttle valve 141, a filter 142, a support member 143, and the like, are fitted to a joint body 140. The joint 122 has a through hole 147. The through hole 147 includes a large-diameter portion 144, a taper portion 145 and a small-diameter portion 146 in the stated order from the body 121-side toward a pipe 125. The taper portion 145 functions as a throttle valve seat, and the taper portion 145-side opening of the small-diameter portion 146 is a throttle valve orifice of the throttle valve seat.
The throttle valve 141 includes a throttle valve element 149, a valve chamber forming member 150 and a coil spring 151. The throttle valve element 149 is provided so as to make contact with and separate from the taper portion 145 (the throttle valve seat). The valve chamber forming member 150 defines a valve chamber in which the throttle valve element 149 is accommodated. The coil spring 151 urges the throttle valve element 149 toward the taper portion 145 (the throttle valve seat). The distal end of the throttle valve element 149 has a taper surface. The taper surface makes contact with and separates from the taper portion 145 (throttle valve seat).
The support member 143 is fitted into the large-diameter portion 144, and has an axial hole 148 that communicates with the valve orifice 135. The filter 142 has a cylindrical shape. Both ends of the filter 142 are respectively fitted to the outer peripheral surface of a support portion of the support member 143 and the outer peripheral surface of a small cylindrical portion of the valve chamber forming member 150. A gasket 152 in a compressed state is disposed between one of the ends of the filter 142 and the support member 143, and another gasket 152 in a compressed state is disposed between the other of the ends of the filter 142 and the valve chamber forming member 150. The valve chamber forming member 150 has a slit for providing communication between the small-diameter portion 146 and the large-diameter portion 144 at the time when the throttle valve element 149 moves in a valve opening direction. Each of the filter 142, the support member 143 and the valve chamber forming member 150 is made of metal.
In the thus configured valve device, hydrogen gas is supplied from the pipe 125 to the supply passage 124 via the joint 122. At this time, because the throttle valve element 149 is provided in the joint 122, the throttle valve element 149 separates from (moves away from) the taper portion 145 (the throttle valve seat) by the pressure of hydrogen gas flowing from the pipe 125-side to the supply passage 124-side, with the result that the opening area of the throttle valve orifice increases. Thus, a large amount of hydrogen gas is allowed to flow from the pipe 125-side to the supply passage 124-side, and therefore, hydrogen gas is quickly supplied to the gas tank.
The end faces of the filter 142 are respectively sealed by the gaskets 152. The gaskets 152 are generally made of a gasket material, such as rubber, synthetic resin and metal. One of the gaskets 152 is disposed between the support member 143 and the filter 142, and the other one of the gaskets 152 is disposed between the filter 142 and the valve chamber forming member 150. Each of the gaskets 152 is sandwiched between the members made of metal. The filter 142 and the valve chamber forming member 150 are not fixed to the joint body 140. Therefore, the gaskets 152 are squashed when the throttle valve element 149 is moved in the valve opening direction to press the valve chamber forming member 150 due to gas pressure at the time of supplying gas. As a result, the gaskets 152 may be excessively squashed.